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	$150.95	7.610%	$162.4373	$162.44	$162.45	$162.40
Purchase #2	$191.82	10.268%	$211.5161	$211.52	$211.50	$211.50
Purchase #3	$32.59	10.388%	$35.9754	$35.98	$36.00	$36.00
Purchase #4	$190.33	13.166%	$215.3888	$215.39	$215.40	$215.40
Purchase #5	$137.63	3.825%	$142.8943	$142.89	$142.90	$142.90
Purchase #6	$223.76	13.349%	$253.6297	$253.63	$253.65	$253.60
Purchase #7	$67.45	9.234%	$73.6783	$73.68	$73.70	$73.70
7 purchase totals =	$994.53		$1,095.5199	$1,095.53	$1,095.60	$1,095.50