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	$200.71	5.159%	$211.0646	$211.06	$211.05	$211.10
Purchase #2	$225.68	9.477%	$247.0677	$247.07	$247.05	$247.10
Purchase #3	$32.91	12.795%	$37.1208	$37.12	$37.10	$37.10
Purchase #4	$36.83	10.118%	$40.5565	$40.56	$40.55	$40.60
Purchase #5	$93.43	5.301%	$98.3827	$98.38	$98.40	$98.40
Purchase #6	$142.98	6.854%	$152.7798	$152.78	$152.80	$152.80
Purchase #7	$218.27	3.755%	$226.466	$226.47	$226.45	$226.50
7 purchase totals =	$950.81		$1,013.4381	$1,013.44	$1,013.40	$1,013.60