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	$141.73	4.188%	$147.6657	$147.67	$147.65	$147.70
Purchase #2	$29.52	6.581%	$31.4627	$31.46	$31.45	$31.50
Purchase #3	$168.57	8.842%	$183.475	$183.48	$183.50	$183.50
Purchase #4	$137.83	12.293%	$154.7734	$154.77	$154.75	$154.80
Purchase #5	$32.63	5.151%	$34.3108	$34.31	$34.30	$34.30
Purchase #6	$67.77	5.185%	$71.2839	$71.28	$71.30	$71.30
Purchase #7	$210.62	10.775%	$233.3143	$233.31	$233.30	$233.30
7 purchase totals =	$788.67		$856.2858	$856.28	$856.25	$856.40