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	$90.91	4.650%	$95.1373	$95.14	$95.15	$95.10
Purchase #2	$118.75	12.188%	$133.2233	$133.22	$133.20	$133.20
Purchase #3	$79.96	13.124%	$90.454	$90.45	$90.45	$90.50
Purchase #4	$180.64	3.263%	$186.5343	$186.53	$186.55	$186.50
Purchase #5	$190.69	13.217%	$215.8935	$215.89	$215.90	$215.90
Purchase #6	$149.84	4.764%	$156.9784	$156.98	$157.00	$157.00
Purchase #7	$10.39	10.846%	$11.5169	$11.52	$11.50	$11.50
7 purchase totals =	$821.18		$889.7377	$889.73	$889.75	$889.70