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	$215.89	3.241%	$222.887	$222.89	$222.90	$222.90
Purchase #2	$33.52	6.250%	$35.615	$35.62	$35.60	$35.60
Purchase #3	$165.53	5.313%	$174.3246	$174.32	$174.30	$174.30
Purchase #4	$42.56	4.646%	$44.5373	$44.54	$44.55	$44.50
Purchase #5	$140.44	10.119%	$154.6511	$154.65	$154.65	$154.70
Purchase #6	$211.69	5.722%	$223.8029	$223.80	$223.80	$223.80
Purchase #7	$248.31	8.259%	$268.8179	$268.82	$268.80	$268.80
7 purchase totals =	$1,057.94		$1,124.6358	$1,124.64	$1,124.60	$1,124.60