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	$172.62	13.611%	$196.1153	$196.12	$196.10	$196.10
Purchase #2	$60.33	3.270%	$62.3028	$62.30	$62.30	$62.30
Purchase #3	$228.54	10.103%	$251.6294	$251.63	$251.65	$251.60
Purchase #4	$196.48	5.115%	$206.53	$206.53	$206.55	$206.50
Purchase #5	$107.58	6.515%	$114.5888	$114.59	$114.60	$114.60
Purchase #6	$89.49	4.672%	$93.671	$93.67	$93.65	$93.70
Purchase #7	$86.54	6.248%	$91.947	$91.95	$91.95	$91.90
7 purchase totals =	$941.58		$1,016.7843	$1,016.79	$1,016.80	$1,016.70