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	$70.88	7.329%	$76.0748	$76.07	$76.05	$76.10
Purchase #2	$199.97	5.700%	$211.3683	$211.37	$211.35	$211.40
Purchase #3	$57.37	7.815%	$61.8535	$61.85	$61.85	$61.90
Purchase #4	$148.82	9.494%	$162.949	$162.95	$162.95	$162.90
Purchase #5	$245.89	9.291%	$268.7356	$268.74	$268.75	$268.70
Purchase #6	$144.95	5.115%	$152.3642	$152.36	$152.35	$152.40
Purchase #7	$206.66	7.633%	$222.4344	$222.43	$222.45	$222.40
7 purchase totals =	$1,074.54		$1,155.7798	$1,155.77	$1,155.75	$1,155.80