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	$196.94	7.410%	$211.5333	$211.53	$211.55	$211.50
Purchase #2	$164.77	12.281%	$185.0054	$185.01	$185.00	$185.00
Purchase #3	$240.59	5.207%	$253.1175	$253.12	$253.10	$253.10
Purchase #4	$213.81	11.678%	$238.7787	$238.78	$238.80	$238.80
Purchase #5	$14.74	4.129%	$15.3486	$15.35	$15.35	$15.30
Purchase #6	$127.36	11.408%	$141.8892	$141.89	$141.90	$141.90
Purchase #7	$44.55	12.470%	$50.1054	$50.11	$50.10	$50.10
7 purchase totals =	$1,002.76		$1,095.7781	$1,095.79	$1,095.80	$1,095.70