Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$148.74	13.501%	$168.8214	$168.82	$168.80	$168.80
Purchase #2	$215.84	11.245%	$240.1112	$240.11	$240.10	$240.10
Purchase #3	$142.30	6.402%	$151.41	$151.41	$151.40	$151.40
Purchase #4	$110.29	12.507%	$124.084	$124.08	$124.10	$124.10
Purchase #5	$144.82	11.148%	$160.9645	$160.96	$160.95	$161.00
Purchase #6	$67.79	7.435%	$72.8302	$72.83	$72.85	$72.80
Purchase #7	$167.51	6.443%	$178.3027	$178.30	$178.30	$178.30
7 purchase totals =	$997.29		$1,096.5240	$1,096.51	$1,096.50	$1,096.50