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	$149.84	8.400%	$162.4266	$162.43	$162.45	$162.40
Purchase #2	$170.95	8.664%	$185.7611	$185.76	$185.75	$185.80
Purchase #3	$203.45	4.593%	$212.7945	$212.79	$212.80	$212.80
Purchase #4	$95.30	8.384%	$103.29	$103.29	$103.30	$103.30
Purchase #5	$32.44	13.298%	$36.7539	$36.75	$36.75	$36.80
Purchase #6	$124.88	13.340%	$141.539	$141.54	$141.55	$141.50
Purchase #7	$168.56	6.358%	$179.277	$179.28	$179.30	$179.30
7 purchase totals =	$945.42		$1,021.8421	$1,021.84	$1,021.90	$1,021.90