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	$198.53	10.492%	$219.3598	$219.36	$219.35	$219.40
Purchase #2	$30.92	4.570%	$32.333	$32.33	$32.35	$32.30
Purchase #3	$84.69	13.189%	$95.8598	$95.86	$95.85	$95.90
Purchase #4	$250.76	11.310%	$279.121	$279.12	$279.10	$279.10
Purchase #5	$233.80	12.534%	$263.1045	$263.10	$263.10	$263.10
Purchase #6	$92.78	11.432%	$103.3866	$103.39	$103.40	$103.40
Purchase #7	$173.87	3.470%	$179.9033	$179.90	$179.90	$179.90
7 purchase totals =	$1,065.35		$1,173.0680	$1,173.06	$1,173.05	$1,173.10