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	$186.28	5.357%	$196.259	$196.26	$196.25	$196.30
Purchase #2	$173.27	6.479%	$184.4962	$184.50	$184.50	$184.50
Purchase #3	$102.53	11.512%	$114.3333	$114.33	$114.35	$114.30
Purchase #4	$173.72	12.673%	$195.7355	$195.74	$195.75	$195.70
Purchase #5	$159.48	13.312%	$180.71	$180.71	$180.70	$180.70
Purchase #6	$152.89	12.821%	$172.492	$172.49	$172.50	$172.50
Purchase #7	$5.65	10.402%	$6.2377	$6.24	$6.25	$6.20
7 purchase totals =	$953.82		$1,050.2637	$1,050.27	$1,050.30	$1,050.20