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	$180.26	9.303%	$197.0296	$197.03	$197.05	$197.00
Purchase #2	$134.93	6.224%	$143.328	$143.33	$143.35	$143.30
Purchase #3	$174.50	9.393%	$190.8908	$190.89	$190.90	$190.90
Purchase #4	$32.45	3.166%	$33.4774	$33.48	$33.50	$33.50
Purchase #5	$163.88	11.134%	$182.1264	$182.13	$182.15	$182.10
Purchase #6	$48.93	13.165%	$55.3716	$55.37	$55.35	$55.40
Purchase #7	$131.31	8.355%	$142.281	$142.28	$142.30	$142.30
7 purchase totals =	$866.26		$944.5048	$944.51	$944.60	$944.50