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	$105.94	4.532%	$110.7412	$110.74	$110.75	$110.70
Purchase #2	$127.38	13.309%	$144.333	$144.33	$144.35	$144.30
Purchase #3	$206.63	4.826%	$216.602	$216.60	$216.60	$216.60
Purchase #4	$142.81	3.338%	$147.577	$147.58	$147.60	$147.60
Purchase #5	$131.86	11.683%	$147.2652	$147.27	$147.25	$147.30
Purchase #6	$240.88	8.733%	$261.9161	$261.92	$261.90	$261.90
Purchase #7	$136.31	3.729%	$141.393	$141.39	$141.40	$141.40
7 purchase totals =	$1,091.81		$1,169.8275	$1,169.83	$1,169.85	$1,169.80