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	$41.48	4.154%	$43.2031	$43.20	$43.20	$43.20
Purchase #2	$142.34	8.131%	$153.9137	$153.91	$153.90	$153.90
Purchase #3	$181.47	6.217%	$192.752	$192.75	$192.75	$192.80
Purchase #4	$121.76	4.398%	$127.115	$127.12	$127.10	$127.10
Purchase #5	$76.85	12.396%	$86.3763	$86.38	$86.40	$86.40
Purchase #6	$172.73	13.674%	$196.3491	$196.35	$196.35	$196.30
Purchase #7	$226.72	8.287%	$245.5083	$245.51	$245.50	$245.50
7 purchase totals =	$963.35		$1,045.2175	$1,045.22	$1,045.20	$1,045.20